The invention relates to a linear separation, as smooth as possible, of a first element with respect to a second element, which are rigidly connected beforehand. The invention is preferably applicable to spatial launchers, for separating stages from each other or the stage and a payload, of missiles, space probes, or even planes, in the case of a payload release. The purpose of this separation is to reduce the weight of the on-board assembly, or to release a payload. These applications are characterized in that there is a need for separating objects that may be fragile, for example a satellite, and the connection of which has had to undergo high mechanical loads, as those undergone when propelled by a launcher.
FIGS. 1A and 1B illustrate the principle of separation between two elements 1 and 2 of a launcher. The first element 1 is preferably an element with the rank n, preferably a first engine stage. The second element is an element with the rank n+1, either a second engine element, or a payload, for example a satellite. The linear separation, in the launcher axis, thus has to be carried out without deteriorating the base of the second element and, in the case where it is desired to recover the first element 1, without deteriorating the surface thereof, where the connection between both these elements 1 and 2 was located.
In the current state of the art, the connecting/separating system is mostly of four types, which are the following ones:                1) the connections by bolting, riveting and pyrotechnic cutting off by pressure and local temperature rise of the structure. These systems, due to their operation, generate ejected material debris. Moreover, the cutting off causes a significant impact in the structure, which may be damageable for the payloads of the launcher;        Patent document FR 2,947,808 shows an example of implementing such a solution.        2) The connections by bolting, riveting and pyrotechnic cutting off by rupturing the structure, through the deformation of a pyrotechnic element. This solution is the most employed and does not generate debris, but causes a very significant impact;        3) the connections by pyrotechnic bolting and rupturing or separating the nut. This type of solution generates much less impact than the two previous ones, but requires several bolts to transmit strains from one element to the other, thus generating higher failure risks because of the number of devices involved;        4) the connections by straps and rupturing the same by pyrotechnic bolts. This type of solution does not enable high strains to be transmitted between both elements and does not allow for too large of diameters for the launchers. Also in this case, the stress relief causes a high impact in the structures.        
Generally, in the current state of these techniques, systems coming from these connecting-separating solutions have the feature of leaving, most of the time, asperities on the external shape of the launcher, after the separation.
The purpose of the invention is to overcome the abovementioned drawbacks.